This article is a listing and an analysis of the world's largest cities (those with a population exceeding 10 million), and of their natural disaster risk level in a variety of categories. My list includes 23 cities, which represent a combined population of approximately 380 million people. That's roughly 5% of the world's population. Listing and population figures based on Wikipedia's list of metropolitan areas by population.

The world's largest cities. Satellite image courtesy of Google Maps.

The list

City

Country

Population (millions)

Natural disaster risks

Tokyo

Japan

32.45

Summary: very well-prepared for high risk of flooding, storms, and earthquakes.

Flood refers to risk of the metropolitan area itself becoming inundated with water.

Storm refers to risk of disaster storms (as opposed to regular storms), which are variously called "hurricanes", "cyclones", "monsoons", "typhoons", and other names (depending on region / climate).

Fire refers to risk of wildfire / bushfire (as opposed to urban fire) from forest or wilderness areas surrounding or within the metropolitan area.

Earthquake refers to risk of the metropolitan area itself being shaken by seismic activity.

Tsunami refers to risk of a seismically-trigged ocean wave hitting the metropolitan area itself.

Drought refers to risk of drought affecting the agricultural region in which the metropolitan area lies.

Analysis

The list above presents quite the sobering picture: of the 23 cities analysed, 9 are critically unprepared for one or more high risks; 10 could be better prepared for one or more high risks; and only 4 are well-prepared for high risks (of which there's one that has no high risks). All in all, the majority of the inhabitants of the world's largest cities live with a signficant risk of natural disaster, for which the city is not sufficiently well-prepared.

By far the most common natural disaster plaguing the list is flooding: it affects 19 of the 23 cities (with many of these cities also at risk from storms). This is understandable, since the majority of the world's large cities are situated on the coast. 15 of the 23 cities in the list are on or very near to the seashore. What's more, about half of the 23 cities are also on or very near to a river delta, with several of them being considered "mega-delta cities" – that is, cities whose metropolitan area lies within a flood-plain.

With the methodology I've used in this analysis, it doesn't really matter what the risk of a given natural disaster striking a city is; what's significant, is how prepared a given city is to handle its most high-risk disasters. After all, if a city is very well-prepared for a high risk, then a large part of the risk effectively cancels itself out (although the risk that remains is still significant, as some cities are at risk of truly monumental disasters for which one can never fully prepare). On the other hand, if a city is critically unprepared for a high risk, this means that really there are no mitigating factors – that city will suffer tremendously when disaster hits.

It should come as no surprise, therefore, that the summary / risk level for each city depends heavily on that country's level of development. For example, the Japanese cities are some of the most disaster-prone cities in the world; but they're also safer than numerous other, less disaster-prone cities, because of Japan's incredibly high level of preparedness for natural disasters (in particular, its world-class earthquake-proof building standards, and its formidable flood-control infrastructure). At the other extreme, the Indian cities are significantly less disaster-prone than many others (in particular, India has a low earthquake risk); but they're more dangerous, due to India's poor overall urban infrastructure, and its poor or non-existent flood-control infrastructure.

Conclusion

So: if you're picking one of the world's largest cities to live in, which would be a good choice? From the list above, the clear winner is Moscow, which is the only city with no high risk of any of the world's more common natural disasters. However, it does get pretty chilly there (Moscow has the highest latitude of all the cities in the list), and Russia has plenty of other issues aside from natural disasters.

The other cities in my list with a tick of approval are the Japanese mega-cities, Tokyo and Osaka. Although Japan is one of the most earthquake-prone places on Earth, you can count on the Japanese for being about 500 years ahead of the rest of the world earthquake-proof-wise, as they are about 500 years ahead of the rest of the world technology-wise in general. Hong Kong would also be a good choice, in picking a city very well-prepared for the natural disasters that it most commonly faces.

For all of you that are living in the other mega-cities of the developed world: watch out, because you're all living in cities that could be better prepared for natural disasters. I'm looking at you Seoul, New York, Los Angeles, London, and Paris. Likewise to the cities on the list in somewhat less-developed countries: i.e. Mexico City, São Paulo, Cairo, Buenos Aires, and Rio de Janeiro. You're all lagging behind in natural disaster risk management.

As for the cities on my list that are "in the red": you should seriously consider other alternatives, before choosing to live in any of these places. The developing nations of Indonesia, India, China, The Philippines, Bangladesh, and Pakistan are home to world mega-cities; however, their population bears (and, in many cases, regularly suffers) a critical level of exposure to natural disaster risk. Jakarta, Delhi, Mumbai, Shanghai, Manila, Kolkata, Dhaka, Beijing, and Karachi: thinking of living in any of these? Think again.